The present invention relates to catheter systems for delivering stents.
A type of endoprosthesis device, commonly referred to as a stent, may be placed or implanted within a vein, artery or other tubular body organ for treating occlusions, stenoses, or aneurysms of a vessel by reinforcing the wall of the vessel or by expanding the vessel. Stents have been used to treat dissections in blood vessel walls caused by balloon angioplasty of the coronary arteries as well as peripheral arteries and to improve angioplasty results by preventing elastic recoil and remodeling of the vessel wall. Two randomized multicenter trials have recently shown a lower restenosis rate in stent treated coronary arteries compared with balloon angioplasty alone (Serruys, P W et al. New England Journal of Medicine 331: 489-495, 1994, Fischman, D L et al. New England Journal of Medicine 331:496-501, 1994). Stents have been successfully implanted in the urinary tract, the bile duct, the esophagus and the tracheo-bronchial tree to reinforce those body organs, as well as implanted into the neurovascular, peripheral vascular, coronary, cardiac, and renal systems, among others. The term xe2x80x9cstentxe2x80x9d as used in this Application is a device which is intraluminally implanted within bodily vessels to reinforce collapsing, dissected, partially occluded, weakened, diseased or abnormally dilated or small segments of a vessel wall.
One of the drawbacks of conventional stents is that they are generally produced in a straight tubular configuration. The use of such stents to treat diseased vessels at or near a bifurcation (branch point) of a vessel may create a risk of compromising the degree of patency of the primary vessel and/or its branches, or the bifurcation point and also limits the ability to insert a branch stent into the side branch if the result of treatment of the primary, or main, vessel is suboptimal. Suboptimal results may occur as a result of several mechanisms, such as displacing diseased tissue, plaque shifting, vessel spasm, dissection with or without intimal flaps, thrombosis, and embolism.
As described in related copending U.S. patent application Nos. 08/744,022, filed Nov. 4, 1996, now abandoned; 09/007,265, filed Jan. 14, 1998; 08/935,383, filed Sep. 23, 1997; and 60/088,301, filed Jun. 5, 1998; and PCT Patent Application WO 99/00835, filed Jan. 14, 1998; systems have been developed for deploying a primary stent in a primary vessel at the intersection of a primary vessel and a branch vessel with a branch stent extending into a branch vessel through a side opening in the primary stent. Unfortunately, several difficulties exist when attempting to position such an arrangement of a primary and branch stents at a vessel intersection.
For example, the insertion of separate guidewires into both the primary vessel and the secondary vessel is required before positioning a primary stent in a primary vessel with a branch stent projecting through a side opening in the primary stent into a branch vessel. Primary and branch stents are then advanced over the separate guidewires which have been pre-guided one after another into the respective primary and branch vessels, such that the primary stent can be deployed within the primary vessel and the branch stent can be deployed through the side opening in the primary stent into the branch vessel. Unfortunately, when attempting to guide two such separate guidewires through the primary vessel such that one enters the branch vessel, the two guidewires typically tend to wrap around one another and become entangled. Additionally, time and effort is required to individually position each of the two guidewires one after another.
An additional disadvantage of conventional stents is the difficulty in visualizing the stents during and after deployment, and in general, the fact that they are not readily imaged by low-cost and easy methods, such as x-ray or ultrasound imaging.
The present invention comprises a dual lumen catheter system having a guidewire received through the first lumen. A side sheath, (or alternatively, a second catheter), is slidably receivable within the second lumen of the dual lumen catheter. As will be explained, an advantage of the present dual lumen catheter system is that it may be used for deploying a primary stent in a primary vessel and a branch stent in a branch vessel, wherein the branch stent is deployed through an opening in the side of the primary stent with the side opening being in registry with the ostium of the branch vessel. An advantage of the present dual lumen catheter system is that it avoids having to separately position first and second guidewires within the respective primary and branch vessels prior to deployment of primary and branch stents thereover. Rather, with the present invention, only a single guidewire needs to initially be placed within the primary vessel, with the present dual lumen catheter system subsequently deploying both the primary and branch stents thereover.
The present invention also sets forth methods for aligning a side opening of a primary stent in registry with the ostium of a branch vessel using the present dual lumen catheter system. In a preferred aspect of the method, a first guidewire is positioned within the primary vessel such that a distal end of the first guidewire extends past a intersection of the primary vessel and the branch vessel. A primary stent is then advanced over the guidewire with the dual lumen catheter, wherein the first guidewire is received within a first lumen of the first catheter. The second lumen of the dual lumen catheter may preferably be formed by attaching a side portion to the dual lumen catheter.
The second lumen of the dual lumen catheter is preferably formed from polyamide and lubricated on its inner surface with graphite particles to make its interior surface microscopically rough thereby reducing sliding friction when a side sheath or second catheter is passed therethrough. Accordingly, the distal end of the side sheath, (which is received through the second lumen of the dual lumen catheter), can easily be slidably positioned to a desired location at the intersection of the primary and branch vessels such that the dual lumen catheter can be positioned at a desired location to deploy the primary stent within the primary vessel. After the distal end of the side sheath is positioned at the vessel intersection, a second guidewire can then be advanced through the side sheath to pass out of the distal end of the side sheath, (passing through the side opening in the primary stent and into the branch vessel), thereby aligning the side opening of the primary stent in registry with the ostium of the branch vessel. Thereafter, the primary stent may be deployed within the primary vessel, such as by inflating a first balloon disposed over the first guidewire at a distal end of the dual lumen catheter.
The present invention also comprises a method of delivering primary and branch stents into the intersection of a primary vessel and a branch vessel such that a side opening in the primary stent is positioned in registry with the ostium of the branch vessel, and such that the branch stent extends through the side opening in the primary stent and into the branch vessel. In a preferred aspect, this is accomplished by deploying a primary stent within the primary vessel such that a side opening in the primary stent is registry with the ostium of the branch vessel with a second guidewire passing out through the side opening in the primary stent and into the branch vessel as described above. A branch stent is then subsequently advanced over the second guidewire and into the branch vessel such that the branch stent passes out through the side opening in the primary stent and into the branch vessel. The primary stent may optionally include radially expandable portions which protrude outwardly from the side opening in the primary stent and into the walls of the branch vessel, holding the side opening in registry with the ostium of the branch vessel.
To deploy the branch stent, the side sheath can be removed from the second lumen of the dual lumen catheter leaving the second guidewire in position in the branch vessel. In addition, the entire catheter system can be removed leaving the two guidewires in place such that the second catheter can be advanced over the second guidewire and into the branch vessel. As such, the second catheter can then be advanced over the second guide wire with its distal end extending into the branch vessel. A second balloon disposed over the second guidewire at a distal end of the second catheter can then be used to deploy the branch stent within the branch vessel. The branch stent may optionally comprise a contact portion at its proximal end to secure the proximal end of the branch stent to the side opening in the primary stent.
In preferred aspects of the present invention, the distal end of the side sheath is positioned at the intersection of the primary vessel and the branch vessel by viewing its position under fluoroscopy. Also, in preferred aspects, the second guidewire is inserted through the side sheath and into the branch vessel under fluoroscopic viewing.
The present invention also comprises an apparatus for aligning a side opening in a primary stent in registry with the ostium of the branch vessel, comprising a dual lumen catheter system in which a first guidewire is slidably received within a first lumen in the catheter and a side sheath is slidably received within the second lumen of the dual lumen catheter. A second guidewire is slidably received within the lumen of the side sheath. To assist in guiding the second guidewire into the branch vessel, the side sheath may preferably taper to a narrow distal end, which may be curved slightly outwardly and which preferably comprises tungsten or other suitable radiopaque material such that it may be fluoroscopically viewed. In other preferred aspects, a first balloon is disposed over the first guidewire at a distal end of the dual lumen catheter and a second balloon is disposed over the second guidewire at a distal end of a second catheter which can be received within the second lumen of the dual lumen catheter.
Applications of the present system include the cardiac, coronary, renal, peripheral vascular, gastrointestinal, pulmonary, urinary and neurovascular systems and the brain. Further advantages of the present dual lumen catheter system are that it provides an improved stent delivery apparatus, which may deliver primary and branch stents to: 1) completely cover the bifurcation point of bifurcation vessels; 2) be used to treat lesions in one branch of a bifurcation while preserving access to the other branch for future treatment; 3) allow for differential sizing of the stents in a bifurcated stent apparatus even after a primary stent is implanted; 4) treat bifurcation lesions in a bifurcated vessel where the branch vessel extends from the side of the primary vessel; and 5) be marked with, or at least partly constructed of, material which is imageable by commonly used intraluminal catheterization visualization techniques including but not limited to ultrasound or x-ray.